Nickel plating additives



United States Patent O 2,994,648 NICIGIL PLATING ADDITIVES Arthur H. Du Rose, Euclid, Ohio, assignor to The Hatshaw Chemical Company, Cleveland, Ohio, at corporation of Ohio No Drawing. Filed Apr. 22, 1960, Ser. No. 23,900 Claims. (Cl. 204-49) This invention relates to the electrodeposition of nickel and more specifically to a process of electrodepositing nickel, and to a solution for use in a process for electrodepositing nickel. The invention has to do with the discovery of cooperating brightening agents suitable for use in aqueous acid nickel plating solutions where the solution contains a nickel electrolyte selected from nickel sulfate and nickel chloride and mixtures thereof.

According to the discovery, excellent bright, ductile and smooth deposits of nickel can be produced over a wide cathode current density range by electrolyzing an aqueous acid solution of a nickel electrolyte of the class consisting of nickel sulfate, nickel chloride and mixtures of nickel sulfate and nickel chloride if the solution also contains an effective amount of each of two cooperating addition agents.

One of the cooperating addition agents has an internal sulfur atom in the organic molecule and is characterized by a solubility in the plating solution of at least 0.00.05 gram per liter and the following characteristic structure:

wherein X is a member selected from the group consisting of and n and m are integers from 1 to 4, and A is a member selected from the group consisting of H, CN--, CN-(CH O-, where p is an integer from 1 to 4, CN-(CH X-, where p is an integer from 1 to 4 and Where X is a member selected from the group consisting of and B is a member selected from the group consisting of --CN, CN(CH -O, where p is an integer from 1 to 4 and CN(CH -X, where p is an integer from 1 to 4 and X is a member selected from the group consisting of The preferred types are the symmetrical forms NC-(OH --X-(CH ),,CN

where X is a member selected from the group consisting of O, and S-- and n is an integer from 1 to 4, which may be called sulfonylalkylene uitriles and sulfinylalkyleue nitriles.

The addition agents falling Within this classification will hereafter be referred to as brighteners. Typical brighteners according to the invention are indicated in Table I. The optimum range of each brightener which should be dissolved in the plating solution is also indicated in Table I in grams of brightener per liter of plating solution. They may be used in the plating solution in concentration from 0.0005 to 0.10 gram per liter.

Table I Optimum Range, Grams per Liter (1) Bis(B-cyanoethyl) sulfone. 0. 005-0. 03

NCCHr-CHaSCHzCHnCN (2) 1,4-Bis(B-cyanoethylsulfonyDbutane 0. 005-0. 03

t NCCHzCHz-%C4Hs-fiCH2CHa-CN O 0 (3) Bis(B-cyanoethyll nlfnxi 0. 005-0. 03

NCCH2CHzS-CH2CH2CN (4) B-cyanoethyl propyl sulioxide 0. 008-0. 05

CHa-CHPCHrfi-CHz-Cflg-CN O (6) B-cyanoethyl B-cyanoethoxyethyl sulfone 0. 008-0. 05

H NCCHzCH:OCH2CHr-fi'-CH2CH2CN (6) Bis(B-cyanoethoxyethy1)su1t'one 0. 008-0. 05

II NC--CH1CHz-OCH1CH2fiCHzCHzO-CH:CH2CN carrier is dissolved in the plating solution in amounts from about 2 to about 5 grams per liter.

Table II AROMATIO SULFONAMIDES benzene monosulfonamide saccharine, sodium salt p-toluenesulfonamide trichlorodtbenzenesulfonamide di-B-naphthalenesinfon amide- 4-carboxydibenzenesulfonamid e N, N-bis(phenylsultony1)-4, 4'-dephenyl sulfonamide p, p-oxy-bis (dibenzeuesulfonamide) p, p'-Inethylene bis-(dibensenesullonamide) AROMATIO SULF ONATES benzene monosulfonic acid benzene disulfonic acid nickel naphthalene disulfonate cobalt naphthalene disulfonate nickel benzene monosulr'onate.-- dicblorobenzene disulionic acid toluene sulfonic acid diphenyl sulfonic acid thiophene sulfonic acid diphenyl sulfone naphthalene trisulfonic acid UNSATURATED ALIPHATIO SULFONAMIDES AND SULFONIO ACIDS Sodium vinyl sulionate sodium allyl sulfonate vinyl sulionamide allyl sulfonamide falls into the category of organic sulfonarnides, sulfimides, and sulfonates. The organic sulfonates, sulfimides and sulfonamides, according to the invention, comprise aromatic and unsaturated aliphatic sulfonates, sulfonamides, and sulfimides. Within the scope of the expression aromatic and unsaturated aliphatic sulfonates, sulfonamides and sulfimides are included the acids and their salts such as the sodium, potassium, nickel, cobalt, and iron salts thereof, Specifically, the class includes aryl and unsaturated alkyl sulfonates, sulfimides and sulfonarnides, and the foregoing salts thereof wherein the number of carbon atoms in any aryl nucleus is from 6 to 10 and in any unsaturated alkyl group is from 1 to 10, and substitution products of the foregoing wherein the substituents are chosen fromthe class of alkyl groups having 1 to 4 carbon atoms, chlorine, CH0 and phenyl. The organic sulfonamides, sulfimides, and sulfonates are frequently referred to as carriers or control agents in the art of nickel plating, and accordingly, are sometimes so-called herein. These carriers produce a degree of brightness without a cooperating brightener. Nevertheless, they do not produce suflicient brightness when uti-' lized as the sole brightening additive in acid nickel plating solutions to be considered as producing a full, bright plate. The carriers or control agents constituting this second class of addition agents have a minimum solubility in the plating solution (for example, in a solution consisting of 240 grams of NiSO .6H O, 37.5 grams of NiCl .6H 0, 37.5 grams of H BO and water to make a liter) to the extent of at least 0.05 gram per liter.

Typical compounds illustrating the aryl and unsaturated alkyl sulfonamides, sulfimides and sulfonates are set forth in Table II. With respect to the aromatic sulfonic acids and sulfonamides and sulfimides various substituents in the ring structure are evident in the formulas in-' dicated.

The brightening addition agent should be dissolved in.

the aqueous plating bath in an amount ranging from 0.0005 to 0.10 gram per liter. Optimum results are usually secured if the concentration of the brighteners The constituents of the plating bath, according to the preferred practice of the invention, are (1) water, (2) nickel sulfate, nickel chloride, or a mixture of nickel sulfate and nickel chloride, (3) the brightener, (4) a sulfonate, a sulfonamide, a sulfimide, or one or more sulfonates, sulfonamides, sulfimides or mixtures thereof of the type previously indicated, and (5) and a wetting agent (optional). An additional ingredient of the solution which is desirable is a buffering agent such as boric acid, formic acid, or the like.

It will be noted that in reference to the major constituent of the nickel plating solution, the solutions are similar to the well known all chloride, all sulfate, and sulfate-chloride or Watts type acid nickel plating solutions. The essential novel feature of the invention is the use of an acid nickel plating solution having one or more nickel electrolytes selected from nickel sulfate and nickel chloride and additionally containing cooperating brightening agents, one of which is at least one carrier selected from the group consisting of unsaturated aliphatic sulfonamides, unsaturated aliphatic sulfimides, unsaturated aliphatic sulfonates, aromatic sulfonamides, aromatic sulfimides and aromatic sulfonates, and the other of which is a small amount of a brightener of the type heretofore indicated.

The basic solutions in connection with which the bright ductile nickel deposits are realized when containing the cooperating addition agents dissolved therein are as follows:

Wetting agent (e.g. sodium lauryl sulfate) 0 to 0.5 grams, preferably 0.05 to 0.2 H20 to make 1000 cc. gram ALL CHLORIDE Wetting agent (e.g. sodium lauryl sulfate) 0 to 0.5 grams, preferably 0.05 t 0.2 120 to make 1000 cc. 0 gram SULFATE-CHLORIDE WATTS TYPE NiSOiJHaO 100 to 400 grams, preferably 25 to 40 grams. to 50 grams, preferably 15 to 40 grams. Wetting agent (e.g. sodium sulfate derivative of 'I-ethyl- 2-methyl-undecanol-4) 0 to 0.5 gram, preferably 0.025 to 0.2 gram. H20 to make 1000 cc.

The plating solutions above identified may be operated under conditions of pH, temperature, and cathode current density which are customarily employed therewith. When the cooperating brightening agents of the invention are dissolved in the plating solutions in the amount previously indicated, bright, ductile deposits Will be obtained upon electrolysis of the solution. Typical operating conditions for the basic solutions are as follows:

All All Watts Sulfate Chloride pH 3-4. 2. 4-4. 5 3-4. 5 Temperature, 120-160 100150 110-155 Cathode Current D 20-40 60-200 30-70 methyl-undecanol-4 and the dihexyl ester of sodium sulfosuccinic acid may be used as an antipitting agent, althoughits use is not essential and other wetting agents or mixtures of wetting agents may be used to control the 5 pitting. For some purposes pitting may be tolerated and sometimes very little pitting occurs.

Specific examples of electroplating solutions containing different cooperating brighteners and carriers are illustrated in. Table III. The operating conditions for obtaining bright ductile nickel deposits are also set forth in the table. In each case a bright nickel deposit of from .05 to about 1 mil thick or thicker, may be secured by electrolyzing the electroplating solution between an anode and a buffed brass cathode. Similar results may be secured on other types of cathodes conventionally employed in acid nickel plating processes utilizing solutions of the type indicated herein.

According to one form of the invention, the addition of coumarin, or certain of its derivatives to the plating solution in amounts from .03 to .25 gram per liter and preferably about .1 gram per liter, materially aids in securing asmooth nickel deposit. Substituted coumarin derivatives Where the substituents are alkylv or acyl groupsnot exceeding 4' carbon atoms, halogen, hydroxy or carboxy groups maybe employed. Typical examples of substituted coumarins are 4-methyl coumarin, 6-chloro coumarin, 3- acetyl coumarin, coumarin-3-carboxylic acid, 4,8-dimethyl coumarin, 7-hydroxy coumarin, 6-carboxy coumarin, 3- chloro coumarin, 3-bromo coumarin, and 3-methyl coumarin. Thus, coumarin or its said derivatives may be dissolved .in the nickel plating solutions containing the cooperating brightening agents and found to exert a leveling or smoothing action such that bright, ductile, nickel deposits of excellent smoothness are obtained.

Table III Nickel Sulfate, g./l Nickel Fluoborate, g./l

Nickel Chloride, g./l Boric Acid, g./l Allyl Sulfonic Acid, g./l

as as as as Dibenzene Suhonamide (Nickel salt), g./l Naphthalene Disulfonate, g./l Ally] Sulfonamide, a /1 Bi-dibenzenesulionamide, 1!

Dibenzenesulfonamide ether, g./1 Sacoharin (sodium salt), g./l Toluene sulfonamide, g./l -t Bis(B-cyanoethyl)sulione, g./l 1,4-Bis(B-cyanoethylsulfonyl) butane, a ll Bis(B-cyanoethy1) sulfoxide, g./l

B-cyanoethyl propyl sulfoxide, g./l B-cyanoethyl B-cyanoethoxyethyl sulfone, g./l

Bis(B-cyanoethoxyethyl) 511E652,

Coumarm, Q 11 Ail 5O 50 C.R.

Nickel Sulfate, g./l Nickel Fluoborate, g./l

Bi-dibenzenesulfonamide, g./l

Dibenzenesulfonamide ether, g./l 3 Saccharin (sodium salt), g./l 2 Toluene sulfonamide, g./l Bis(B-cyanoethyl)sulfone, ll

g, 1,4-Bis(B-cyanoethylsulfonyl)butane, g./l Bis(B-cyanuethyl) sulfoxide, g./l B-cyanoethyl propyl sulfoxide, g./l B-cyanoethyl B-cyanoethoxyethyl sulfone,

Coumarin, ./l

Cathode Current Density (amp.!ft. Temperature, F Agitation 1 1 C.R.=cathode rod.

wherein X is a member selected from the group consisting of and n and m are integers from 1 to 4, and A is a member selected from the group consisting of H, CN, CN(CH O-, where p is an integer from 1 to 4, CN(CH -X, where p is an integer from 1 to 4 and where X is a member selected from the group consisting of and B is a member selected from the group consisting of --CN, CN-(C z) Where p is an integer from 1 to 4, and CN(CH Where p is an integer from 1 to 4 and X is a member selected from the group consisting of i -s 0 II ll 0 and -S the first said brightening addition agent being present in said solution to the extent of from .05 to 20 grams perliter and the second said brightening addition agent being present in said solution to the extent of from 0.0005 to 0.10 gram per liter. l

2. A nickel electroplating bath comprising an aqueous solution of a nickel electrolyte selected from the group] j consisting of nickel sulfate, nickel chloride, and mixtures thereof, said solution'also containing cooperatingbright: H

ening addition agents, one of said brightening addition agents being at least one organic compound selected from the group consisting of aromatic and unsaturated aliphatic sulfonates, sulfonamides and sulfimides and the second of" said agents being a compound of the formula 8.. of said brightening addition agents being a compound of the formula wherein n is an integer from 1 to 4, the first said brightening addition agent being present in said solution to the extent of from .05 to 20 grams per liter and the second said brightening addition agent being present in said solution to the extent of from 0.0005 to 0.10 gram per liter.

4. A nickel electroplating bath comprising an aqueous solution of a nickel electrolyte selected from the group consisting of nickel sulfate, nickel chloride, and mixtures thereof, said solution also containing cooperating brightening addition agents, one of said brightening addition agents being at least one organic compound selected from the group consisting of aromatic and unsaturated aliphatic sulfonates, sulfonamides and sulfimides and the second of said brightening addition agents being a compound of the formula wherein n is an integer from 1 to 4, the first said brightening addition agent being present in said solution to the extent of from .05 to 20 grams per liter and the second said brightening addition agent being present in said solution to the extent of from 0.0005 to 0.10 gram per liter.

5. An acid nickel electroplating solution comprising in addition to Water, nickel sulfate equivalent to from 100 to 400 grams per liter of NiSO -7H O, nickel C1110? ride equivalent to from 10 to 60 grams per liter of NiCl -6H O, a buffering agent and cooperating, brighten ing addition agents, one of said brightening addition agents being a compound selected from the group consisting of aromatic and unsaturated aliphatic sulfonates, sulfonamides and sulfimides and the second of said brightening addition agents being Bis(B-cyanoethyl) sulfone, the first said brightening addition agent being present in said solution to the extent of from 0.05 to 20 grams per liter and the second said brightening addition agent being present in said solution to the extent of from 0.005 to 0.03 gram per liter.

6. An acid nickel electroplating solution comprising in addition to water, nickel sulfate equivalent to from 100 to 400 grams per liter of NiSO -7H O, nickel chlo- Q ride equivalent to from 10 to 60 grams per liter of NiCl -6H O, a buffering agent and cooperating, brightening addition agents, one of said brightening addition and n is an integer from 1 to 4, the first said brightening addition agent being present in said solution to the extent of from .05 to 20 grams per liter and the second said brightening addition agent being present in said solution a to the extent of from 0.0005 to 0.10 gram per liter.

3. A nickel electroplating bath comprising an aqueous '7 solution of a nickel electrolyte selected from the group consisting of nickel sulfate, nickel chloride, and mixtures thereof, said solution also containing cooperating'brightening addition agents, one of said brightening addition agents being at least one organic compound selected from the group consisting of aromatic and unsaturated aliphatic sulfonates, sulfonamides and sulfimides and t e second agents being a compound selected from the group consisting of aromatic and unsaturated aliphatic sulfonates, sulfonamides and sulfimides and the second of said brightening addition agents being a 1,4-Bis(B-cyanoethy1- sulfonyl) butane, the first said brightening addition agent being present in said solution to the extent of from 0.05 to 20 grams per liter and the second said brightening addition agent being present in said solution to the extent of from 0.005 to 0.03 gram per liter.

7. An acid nickel electroplating solution comprising in addition to Water, nickel sulfate equivalent to from to 400 grams per liter of NiSO -7H O, nickel chlo ride equivalent to from 10 to 60 grams per liter of NiCl -6H O, a buffering agent and cooperating, brightening addition agents, one of said brightening addition agents being a compound selected from the group consisting of aromatic and unsaturated aliphatic sulfonates, sulfonamides and sulfimides and the second of said brightening addition agents being a Bis(B-cyanoethyl) sulfoxide, the first said brightening addition agent being present in said solution to the extent of from 0.05 to 20 grams per liter and the second said brightening addition agent being prment in said solution to the extent Of from 0.0005 to 0.006 gram per liter.

8. An acid nickel electroplating solution comprising in addition to water, nickel sulfate equivalent to from 100 to 400 grams per liter of NiSO -7H O, nickel chloride equivalent to from to 60 grams per liter of NiCl -6H O, a buffering agent and cooperating, brightening addition agents, one of said brightening addition agents being a compound selected from the group consisting of aromatic and unsaturated aliphatic sulfonates, sulfonamides and sulfimides and the second of said brightening addition agents being a B-cyanoethyl propyl sulfoxide, the first said brightening addition agent being present in said solution to the extent of from 0.05 to 20 grams per liter and the second said brightening addition agent being present in said solution to the extent of from 0.0005 to 0.006 gram per liter.

9. An acid nickel electroplating solution comprising in addition to water, nickel sulfate equivalent to from 100 to 400 grams per liter of NiSO -7H O, nickel chloride equivalent to from 10 to 60 grams per liter of NiCl -6H O, a bufiering agent and cooperating, brightening addition agents, one of said brightening addition agents being a compound selected from the group consisting of aromatic and unsaturated aliphatic sulfonates, sulfonamides and sulfimides and the second of said brightening addition agents being a B-cyanoethyl B-cyanoethoxyethyl sulfone, the first said brightening addition 10 agent being present in said solution to the extent of from 0.05 to 20 grams per liter and the second said brightening addition agent being present in said solution to the extent of from 0.0005 to 0.006 gram per liter.

10. An acid nickel electroplating solution comprising in addition to water, nickel sulfate equivalent to from 100 to 400 grams per liter of NiSO -7H O, nickel chloride equivalent to from 10 to grams per liter of NiCl -6H O, a buffering agent and cooperating, brightening addition agents, one of said brightening addition agents being a compound selected from the group consisting of aromatic and unsaturated aliphatic sulfonates, sulfonamides and sulfimides and the second of said brightening addition agents being a Bis(B-cyanoethoxyethyl) sulfone, the first said brightening addition agent being present in said solution to the extent of firom 0.05 to 20 grams per liter and the second said brightening addition agent being present in said solution to the extent of from 0.0005 to 0.006 gram per liter.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A NICKEL ELECTROPLATING BATH COMPRISING AN AQUEOUS SOLUTION OF NICKEL ELECTROLYTE SELECTED FROM THE GROUP CONSISTING OF NICKEL SULFATE, NICKEL CHLORIDE, AND MIXTURES THEREOF, SAID SOLUTION ALSO CONTAINING COOPERATING BRIGHTENING ADDITION AGENTS, ONE OF SAID BRIGHTENING ADDITION AGENTS BEING AT LEAST ONE ORGANIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF AROMATIC AND UNSATURATED ALIPHATIC SULFONATES, SULFONAMIDES, AND SULFIMIDES, AND THE SECOND OF SAID BRIGHTENING ADDITION AGENTS BEING A COMPOUND OF THE FORMULA 